Jakeintoledo
Well-Known Member
Folks,
Pardon me, please, if this ground has already been ploughed, but I cannot find where my questions have been addressed after some searching.
I am having difficulty controlling the temperature of my mash using a RIMS system, and would like some recommendations on how to better control this system.
The particulars are this: At the mash cycle, the pump will come on and stay on, and the RTD sensor I have in the kettle (which is positioned to be in the center mass of the grain bed) will indicate the temperature to the controller. The controller senses the temp and controls a solid state relay to turn the heating element on and off.
The Problem: The temperature swing is HUGE. I can target 152, for example, and see a drop down to 147. most of my experiments have involved brews that I wanted to come out successful, so I will ignite the auxiliary propane burner under the kettle to more quickly recover the temp drop. When I do that, I'm really just adding a large error above the setpoint.
I don't know much about how to tune a PID loop, but I know that thermostatic control works very poorly. the temperature decay is faster than the system can correct for, if I set the thermostatic control to come on at .1 degrees below set point, the temperature doesn't start to come back until it's about 2 degrees below setpoint.
I think the answer is a PID loop, but help on tuning it would be helpful. The heater is an on/off control, so a PID output would have to be part of a calculation of a Pulse Width Modulator.
The first image below is of the system; the pump will pump through a semi-transparent flexible tubing to give an indication of fluid present. the enclosure you see is housing the RIMS tube (enclosed for safety). the inlet is on the far side, facing you in the image, and the outlet flows out of the top, back up toward the kettles.
Pardon me, please, if this ground has already been ploughed, but I cannot find where my questions have been addressed after some searching.
I am having difficulty controlling the temperature of my mash using a RIMS system, and would like some recommendations on how to better control this system.
The particulars are this: At the mash cycle, the pump will come on and stay on, and the RTD sensor I have in the kettle (which is positioned to be in the center mass of the grain bed) will indicate the temperature to the controller. The controller senses the temp and controls a solid state relay to turn the heating element on and off.
The Problem: The temperature swing is HUGE. I can target 152, for example, and see a drop down to 147. most of my experiments have involved brews that I wanted to come out successful, so I will ignite the auxiliary propane burner under the kettle to more quickly recover the temp drop. When I do that, I'm really just adding a large error above the setpoint.
I don't know much about how to tune a PID loop, but I know that thermostatic control works very poorly. the temperature decay is faster than the system can correct for, if I set the thermostatic control to come on at .1 degrees below set point, the temperature doesn't start to come back until it's about 2 degrees below setpoint.
I think the answer is a PID loop, but help on tuning it would be helpful. The heater is an on/off control, so a PID output would have to be part of a calculation of a Pulse Width Modulator.
The first image below is of the system; the pump will pump through a semi-transparent flexible tubing to give an indication of fluid present. the enclosure you see is housing the RIMS tube (enclosed for safety). the inlet is on the far side, facing you in the image, and the outlet flows out of the top, back up toward the kettles.